Inner sleeve for a flat extrusion cylinder and a flat extrusion cylinder

ABSTRACT

An inner sleeve for a flat extrusion cylinder includes an inner sleeve ring piece, an upper insert piece and a lower insert piece. The inner sleeve ring piece is positioned in an intermediate sleeve of the flat extrusion cylinder. The upper insert piece and the lower insert piece are symmetrically disposed on an inner wall of the inner sleeve ring piece to form an inner sleeve working die cavity of the flat extrusion cylinder. Arc surfaces of two insert pieces match with the arc inner wall of the inner sleeve ring piece, so as to improve the stress distribution at interface portions between the flat surface and the arc surface of the inner sleeve working die cavity. When the flat extrusion cylinder is operated, the insert pieces will make a minor displacement in upward and downward direction due to the pressure from the inner sleeve working die cavity, such that the inner sleeve ring piece is elastically deformed in a circumferential direction, thereby generating a resisting force against the peak stress in the cylinder. In the flat extrusion cylinder according to the present invention, concentrated internal stress is uniformly transmitted to the inner sleeve ring piece, which decreases the peak stress in dangerous sections and achieves cylinder-type stress distribution in the flat extrusion cylinder. Thus, the stress received by the inner sleeve ring piece is distributed uniformly, thereby increasing the lifespan of the entire flat extrusion cylinder.

The present application claims benefit of the priority to CN application No. 200910148224.6 titled “AN INNER SLEEVE FOR A FLAT EXTRUSION CYLINDER AND A FLAT EXTRUSION CYLINDER”, filed with the Chinese State Intellectual Property Office on Jun. 18, 2009. The entire disclosures thereof are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to mechanical construction technology, and more specifically to an inner sleeve for a flat extrusion cylinder and a flat extrusion cylinder.

BACKGROUND OF THE INVENTION

The flat extrusion cylinder is an indispensable tool for extruding large-sized, flat and wide, thin-wall, complicated hollow and solid profiled material. Since the flat extrusion cylinder usually works in bad conditions such as high temperature, high pressure and high friction, stress distribution is not uniform extremely so that an inner sleeve is prone to rupture, which reduces the working life thereof.

Referring to FIG. 1, FIG. 1 is a schematic view of the flat extrusion cylinder including an integral inner sleeve in the prior art.

As shown in FIG. 1, a flat extrusion cylinder is constituted of an inner sleeve 101, an intermediate sleeve 102 and an outer sleeve 103. The inner sleeve 101 is of an integral structure and has a circular outer profile and a rectangular hole formed therein. Thus, the edges of the rectangular hole will become dangerous sections to rupture, as indicated by the parts enclosed by circles 104 shown in FIG. 1. Due to the machining and manufacture processes, metal streamline of the dangerous section is not regularly distributed in a circumferential direction, which reduces the utilization effect of material. During practical production, the inner sleeve of the large-sized flat extrusion cylinder, 99% rupture is occurred in the dangerous section. As can be seen, the inner sleeve of this structure has a short life.

At present, there also is an assembled-type inner sleeve for flat extrusion cylinder. Referring to FIG. 2, FIG. 2 is a schematic view of a flat extrusion cylinder including an assembled inner sleeve in the prior art.

The assembled inner sleeve is constituted of four assemble pieces, i.e., a left assemble piece A, a right assemble piece B, an upper assemble piece C and a lower assemble piece D, respectively. The four assemble pieces are fixed on an inner wall of an intermediate sleeve.

During operation of the inner sleeve, the left assemble piece A and the right assemble piece B are not subject to tension stress, and the stress generated from a working die cavity is transmitted to the intermediate sleeve 102 by the upper assemble piece C and the lower assemble piece D, and thus the intermediate sleeve 102 is subject to the maximum peak stress. Thus, the lifespan of the intermediate sleeve 102 is significantly decreased. Furthermore, the left assemble piece A and the right assemble piece B only play a role of constituting the working die cavity and transmitting stress because they are not subject to tension stress, so that the space utilization of the flat extrusion cylinder is low and the strength of the flat extrusion cylinder has to be improved only by increasing the outline dimension thereof.

Therefore, for such assembled inner sleeve, the lifespan of the intermediate sleeve is decreased, and the space utilization of the flat extrusion cylinder is low.

Taken together, conventional structures of the inner sleeve for the flat extrusion cylinder lead to a shortened lifespan of the flat extrusion cylinder.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide an inner sleeve for the flat extrusion cylinder and a flat extrusion cylinder, which can increase the lifespan of the flat extrusion cylinder.

The inner sleeve for the flat extrusion cylinder according to the present invention includes an inner sleeve ring piece, an upper insert piece and a lower insert piece;

wherein the inner sleeve ring piece is disposed in an intermediate sleeve of the flat extrusion cylinder; and

wherein the upper insert piece and the lower insert piece are symmetrically disposed on an inner wall of the inner sleeve ring piece to form an inner sleeve working die cavity of the flat extrusion cylinder.

Preferably, each of the upper insert piece and the lower insert piece has crescent-shaped cross-section, and an arc surface of crescent-shaped cross-section matches with an arc surface of the inner sleeve ring piece.

Preferably, the inner sleeve further includes at least two countersunk head bolts configured to fix the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece.

Preferably, the number of the countersunk head bolts is two, that is, a first countersunk head bolt and a second countersunk head bolt, respectively,

wherein the first countersunk head bolt is configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and

wherein the second countersunk head bolt is configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.

Preferably, the number of the countersunk head bolts is four, wherein two of the countersunk head bolts are configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and the other two of the countersunk head bolts are configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.

Preferably, the inner sleeve ring piece is made by forging process.

Preferably, a blank of the inner sleeve ring piece is forged by hole-enlarging shaping process or annular rolling process, so that metal streamline of the inner sleeve ring piece is regularly distributed in a circumferential direction.

The present invention further provides a flat extrusion cylinder including an intermediate sleeve and an outer sleeve, wherein the intermediate sleeve is disposed within the outer sleeve; the flat extrusion cylinder further includes above inner sleeve disposed within the intermediate sleeve.

Comparing with the prior art, the present invention has the following advantages.

The inner sleeve for the flat extrusion cylinder according to the present invention is constituted of the inner sleeve ring piece and two insert pieces. Arc surfaces of the two insert pieces match with the arc inner wall of the inner sleeve ring piece, so as to improve the stress distribution at interface portions between the flat surface and the arc surface of the inner sleeve working die cavity. When the flat extrusion cylinder is operated, the insert pieces will make a minor displacement in upward and downward direction due to the pressure from the inner sleeve working die cavity, such that the inner sleeve ring piece is elastically deformed in the circumferential direction, thereby generating a resisting force against the peak stress in the cylinder. In the flat extrusion cylinder according to the present invention, concentrated internal stress is uniformly transmitted to the inner sleeve ring piece, which decreases the peak stress in dangerous sections and achieves cylinder-type stress distribution in the flat extrusion cylinder. Thus, the stress received by the inner sleeve ring piece is distributed uniformly, thereby increasing the lifespan of the entire flat extrusion cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the flat extrusion cylinder including an integral inner sleeve in the prior art;

FIG. 2 is a schematic view of the flat extrusion cylinder including an assembled inner sleeve in the prior art;

FIG. 3 is a schematic view of a first embodiment of an inner sleeve for a flat extrusion cylinder according to the present invention; and

FIG. 4 is a schematic view of a second embodiment of an inner sleeve for the flat extrusion cylinder according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The above objects, features and advantages of the present invention will become more apparent and may be better understood from the description of the specific embodiments of the present invention with reference to the drawings.

Referring to FIG. 3, FIG. 3 is a schematic view of a first embodiment of an inner sleeve for the flat extrusion cylinder according to the present invention.

The inner sleeve for the flat extrusion cylinder according to this embodiment of the present invention includes an inner sleeve ring piece 301, upper insert piece 302 and lower insert piece 303.

The inner sleeve ring piece 302 is positioned in the intermediate sleeve 102 of the flat extrusion cylinder.

The upper insert piece 302 and lower insert piece 303 are symmetrically located on an inner wall of the inner sleeve ring piece 301, respectively. The upper insert piece 302 and lower insert piece 303 define an inner sleeve working die cavity 304 of the flat extrusion cylinder.

As shown in FIG. 3, each of the upper insert piece 302 and lower insert piece 303 has a crescent-shaped cross-section. An arc surface of the crescent-shaped cross-section matches with the arc surface of the inner sleeve ring piece 301.

The upper insert piece 302 and the lower insert piece 303 form the inner sleeve working die cavity 304 having approximately rectangular shape.

The inner sleeve for the flat extrusion cylinder according to the present invention is constituted of the inner sleeve ring piece 301 and two insert pieces. Arc surfaces of the two insert pieces match with the arc inner wall of the inner sleeve ring piece 301, so as to improve the stress distribution at interface portions between the flat surfaces and the arc surfaces of the inner sleeve working die cavity 304. When the flat extrusion cylinder is operated, the insert pieces will make a minor displacement in upward and downward direction due to the pressure from the inner sleeve working die cavity 304, such that the inner sleeve ring piece 301 is elastically deformed in the circumferential direction thereof, thereby generating a resisting force against the peak stress in the cylinder. In the flat extrusion cylinder according to the present invention, concentrated internal stress is uniformly transmitted to the inner sleeve ring piece 301, which decreases the peak stress in dangerous sections and achieves cylinder-type stress distribution in the flat extrusion cylinder. Thus, the stress received by the inner sleeve ring piece is distributed uniformly, thereby increasing the lifespan of the entire flat extrusion cylinder.

Referring to FIG. 4, FIG. 4 is a schematic view of a second embodiment of an inner sleeve for the flat extrusion cylinder according to the present invention.

The inner sleeve for the flat extrusion cylinder according to this embodiment further includes at least two countersunk head bolts for fixing the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece.

As shown in FIG. 4, this embodiment preferably adopts two countersunk head bolts, i.e., an upper countersunk head bolt 305 and a lower countersunk head bolt 306, respectively.

The upper countersunk head bolt 305 is used to fix the upper insert piece 302 on the inner wall of the inner sleeve ring piece 301.

The lower countersunk head bolt 306 is used to fix the lower insert piece 303 on the inner wall of the inner sleeve ring piece 301.

It is noted that, in order to save material and reduce manufacture process in this embodiment, only two countersunk head bolts are used. Of cause, in order to fix the insert pieces on the inner wall of the ring piece inner sleeve firmly, the number of the countersunk head bolt used may be increased. For example, four countersunk head bolts may be used, two of which are used to fix the upper insert piece, and the others of which are used to fix the lower insert piece.

It is noted that, in this embodiment, the countersunk head bolts are preferably used to fix the insert pieces on the inner wall of the inner sleeve ring piece. Of cause, other ways or members, which are capable of fixing the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece, may be used.

The inner sleeve ring piece according to embodiments is made by forging process. When blank of the inner sleeve ring piece is forged, forging process may be regulated so that the metal streamline of the inner sleeve ring piece is uniformly distributed in the circumferential direction. In this way, the strength of material in the circumferential direction may be increased by 20%˜30%, and the resistance to rupture of the inner sleeve for the flat extrusion cylinder is improved, thereby prolonging the lifespan of the flat extrusion cylinder.

The forging process will be briefly explained below.

Forging is a manufacturing process in which a metal blank is pressed by use of forging machinery and is plastically deformed in order to obtain a forging part having certain mechanical performance, certain shape and dimension. By forging, defects of metal generated in smelting process such as casting porosity can be eliminated and the microstructure of metal is optimized, moreover, the mechanical performance of a forging part is generally superior to that of a casting part made of the same material because the entire metal streamline is kept in the forging part.

A blank of the inner sleeve ring piece of the flat extrusion cylinder according to the present invention is forged by hole-enlarging shaping process or annular rolling process, so that the metal streamline of the inner sleeve ring piece is distributed in the circumferential direction (or in the tangent direction).

In the inner sleeve for the flat extrusion cylinder of the present invention, since the insert pieces make a minor displacement in upward and downward direction due to the pressure from the inner sleeve working die cavity during operation, such that the inner sleeve ring piece is elastically deformed in the circumferential direction, thereby generating a resisting force against the peak stress in the cylinder. The resistant effect in the present invention is better than that of the integral inner sleeve in which the peak stress is resisted by deformation of rectangular edges thereof. The structure of the inner sleeve of the present invention is reasonable, which can effectively and uniformly transmits concentrated internal stress to the inner sleeve ring piece so as to decrease the peak stress in dangerous sections and achieve cylinder-type stress distribution in the flat extrusion cylinder. The present invention relieves the defect that the excessive stress is concentrated in the inner wall of the inner sleeve for the flat extrusion cylinder, and thus the using number of times of the inner sleeve is greatly increased. Therefore, the lifespan of the overall flat extrusion cylinder is increased.

Another embodiment of the present invention further provides a flat extrusion cylinder including an inner sleeve, an intermediate sleeve and an outer sleeve, in which the inner sleeve adopts the structure of the inner sleeve in the above-described embodiments. The inner sleeve is disposed within the intermediate sleeve, and the intermediate sleeve is disposed within the outer sleeve.

This structure of the inner sleeve may increase the lifespan of the inner sleeve, and thus may increase the lifespan of the flat extrusion cylinder.

It is noted that, the structure of the inner sleeve for the flat extrusion cylinder according to embodiments of the present invention neither specifically limits dimensions of the flat extrusion cylinder, nor specifically limits dimensions of the inner sleeve. The flat extrusion cylinder having various dimensions may be manufactured as actual requirements.

Though the preferred embodiments of the present invention have been described above, it is not intended to limit the present invention in any way. The present invention is disclosed by way of the preferred embodiments; however, the present invention is not limited thereto. Any skilled in the art may make many potential changes and modifications to the technical solutions of the present invention, or change the technical solutions of the present invention as equivalent embodiments without depart from the scope of the technical solutions of the present invention by using the above-disclosed method and technology contents. Therefore, any changes, equivalents and modifications made to the above embodiments by using the substantive technology of the present invention without depart from the technical solution of the present invention, falls into the protection scope of the technical solutions of the present invention. 

1. An inner sleeve for a flat extrusion cylinder comprising an inner sleeve ring piece, an upper insert piece and a lower insert piece; wherein the inner sleeve ring piece is disposed in an intermediate sleeve of the flat extrusion cylinder, and wherein the upper insert piece and the lower insert piece are symmetrically disposed on an inner wall of the inner sleeve ring piece to form an inner sleeve working die cavity of the flat extrusion cylinder.
 2. The inner sleeve for the flat extrusion cylinder according to claim 1, wherein each of the upper insert piece and the lower insert piece has crescent-shaped cross-section, and an arc surface of crescent-shaped cross-section matches with an arc surface of the inner sleeve ring piece.
 3. The inner sleeve for the flat extrusion cylinder according to claim 1, further comprising at least two countersunk head bolts configured to fix the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece.
 4. The inner sleeve for the flat extrusion cylinder according to claim 3, wherein the number of the countersunk head bolts is two, that is, a first countersunk head bolt and a second countersunk head bolt, respectively, wherein the first countersunk head bolt is configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and wherein the second countersunk head bolt is configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.
 5. The inner sleeve for the flat extrusion cylinder according to claim 3, wherein the number of the countersunk head bolts is four, wherein two of the countersunk head bolts are configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and the other two of the countersunk head bolts are configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.
 6. The inner sleeve for the flat extrusion cylinder according to claim 1, wherein the inner sleeve ring piece is made by forging process.
 7. The inner sleeve for the flat extrusion cylinder according to claim 6, wherein a blank of the inner sleeve ring piece is forged by hole-enlarging shaping process or annular rolling process, so that metal streamline of the inner sleeve ring piece is regularly distributed in a circumferential direction.
 8. A flat extrusion cylinder comprising an intermediate sleeve and an outer sleeve, wherein the intermediate sleeve is disposed within the outer sleeve, wherein the flat extrusion cylinder further comprises the inner sleeve as claimed in claim 1, and wherein the inner sleeve is disposed within the intermediate sleeve.
 9. The flat extrusion cylinder according to claim 8, wherein each of the upper insert piece and the lower insert piece has crescent-shaped cross-section, and an arc surface of crescent-shaped cross-section matches with an arc surface of the inner sleeve ring piece.
 10. The flat extrusion cylinder according to claim 8, further comprising at least two countersunk head bolts configured to fix the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece.
 11. The flat extrusion cylinder according to claim 10, wherein the number of the countersunk head bolts is two, that is, a first countersunk head bolt and a second countersunk head bolt, respectively, wherein the first countersunk head bolt is configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and wherein the second countersunk head bolt is configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.
 12. The flat extrusion cylinder according to claim 10, wherein the number of the countersunk head bolts is four, wherein two of the countersunk head bolts are configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and the other two of the countersunk head bolts are configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.
 13. The flat extrusion cylinder according to claim 8, wherein the inner sleeve ring piece is made by forging process.
 14. The flat extrusion cylinder according to claim 13, wherein a blank of the inner sleeve ring piece is forged by hole-enlarging shaping process or annular rolling process, so that metal streamline of the inner sleeve ring piece is regularly distributed in a circumferential direction. 